2I 4 
excellent diffusing and toxic powers, and at the same time it was a 
very efficient germicide. It diffused perfectly with water, forming a 
milky emulsion very destructive to mosquito larvae, and having a 
germicidal value of, or greater than, that of pure carbolic acid, ora 
R ideal-Walker co-efficient of one to two. In this way a very valuable 
larvacide and disinfectant, miscible with water, was produced from a 
very inferior disinfectant. 
The larvacidal powers when tried with Culicine and Anopheline 
larvae varied slightly with the quality of the crude carbolic acid, but 
an average result is as follows: 
Dilution i to 1000 — Culicine larvae, dead in 5 minutes. 
Anopheline larvae, halt grown, dead in 5 minutes. 
Anopheline larvae, full grown, dead in 10 minutes. 
Dilution 1 to 5000 Anopheline larvae, half and full grown, dead in 5 minutes. 
Culicine larvae, half grown, dead in 3 minutes. 
Dilution 1 to 10000—Culicine larvae, half grown, dead in 64 minutes. 
Anopheline larvae, young, dead in 52 minutes. 
Anopheline larvae, full grown, dead in 135 minutes. 
Dilution 1 to 15000—Small Culicine larvae, dead in 32 minutes. 
Anopheline larvae, full grown, dead in 123 minutes. 
Anopheline larvae seem to be slightly more resistant than Culicine 
larvae, and all pupae are more resistant to the effects of the larvacide 
than larvae are. 
EXPERIMENTS WITH AGENTS DESTRUCTIVE TO 
VEGETATION, GRASS AND ALGAE 
A seiies of experiments was carried out with the larvacide, caustic 
so a, arsenic and copper sulphate as to the amounts necessary in 
poo s and lagoons to prevent the growth of vegetation and to 
^ rmine t he value of the resulting solutions as larvacides. Bermuda 
fl I* 1 so< ^ VN as made into artificial ponds in large glass moist-jars and 
ce with 05 per cent, solution of caustic soda, copper sulphate 
1 r ^ Ur ' C ac *d- The sod was well soaked with the chemical 
n ’ Ut ^ ie 8 ra ss remained vigorous in each instance. The jars 
n isturbed foi a period of eighteen days, when a number of 
pool TL 16 V ' Cre ’ ntT oduced into the solution of the artificial 
. . 6 ^ arvae weie killed within twenty-four hours in the pools 
coppei sulphate and sulphuric acid; but those in the pool 
